Signals may be defined as information-bearing patterns that convey information about behavior or attribute of some phenomenon and signal detection may be understood as a means to quantify the ability to distinguish between the signals and random energy patterns, such as noise that distract from the information. For example, in case of radar, dots on a screen of the radar confirm the presence of aircrafts. However, the dots may also appear on the screen due to some other object in the environment. In said example, presence of an aircraft may be understood as a signal and presence of the other objects may be understood as noise. In such a case, detection of a dot corresponding to the aircraft may be referred to as signal detection.
Further, various outcomes are possible during detection of the signal, such as a hit, a miss, a false alarm, and a correct rejection. In case of the hit, the dot corresponding to the aircraft is correctly identified. In case of the miss, it is wrongly identified that none of the dots correspond to the aircraft. In case of the false alarm, wrong dot is identified as the aircraft on the screen of the radar. In case of the correct rejection, dots corresponding to the other objects are correctly identified.